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      <h1 id="MyBatis-日志和分页的实现"><a href="#MyBatis-日志和分页的实现" class="headerlink" title="MyBatis 日志和分页的实现"></a>MyBatis 日志和分页的实现</h1><h2 id="日志的实现"><a href="#日志的实现" class="headerlink" title="日志的实现"></a>日志的实现</h2><h3 id="为什么需要日志？"><a href="#为什么需要日志？" class="headerlink" title="为什么需要日志？"></a>为什么需要日志？</h3><ul>
<li>以往的开发过程，我们会经常使用到debug模式来调节，跟踪我们的代码执行过程。</li>
<li>但是现在使用Mybatis是基于接口，配置文件的源代码执行过程。因此，我们必须选择日志工具来作为我们开发，调节程序的工具。</li>
</ul>
<p><strong>Mybatis内置的日志工厂提供日志功能，具体的日志实现有以下几种工具：</strong></p>
<ul>
<li>SLF4J</li>
<li>Apache Commons Logging</li>
<li>Log4j 2</li>
<li>Log4j</li>
<li>JDK logging</li>
</ul>
<a id="more"></a>



<h3 id="标准日志的实现"><a href="#标准日志的实现" class="headerlink" title="标准日志的实现"></a>标准日志的实现</h3><p>指定MyBatis应该是用那个日志记录实现。如果此设置不存在，则会自动发现日志记录实现。</p>
<p>实现方式：在resource文件夹下的mybatisconfig.xml添加</p>
<figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">settings</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">setting</span> <span class="attr">name</span>=<span class="string">"logImpl"</span> <span class="attr">value</span>=<span class="string">"STDOUT_LOGGING"</span>/&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">settings</span>&gt;</span></span><br></pre></td></tr></table></figure>



<p>日志输出结果：</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br></pre></td><td class="code"><pre><span class="line">E:\jdk1<span class="number">.8</span>\bin\java.exe -ea -Didea.test.cyclic.buffer.size=<span class="number">1048576</span> <span class="string">"-javaagent:E:\IntelliJ IDEA 2019.1\lib\idea_rt.jar=54966:E:\IntelliJ IDEA 2019.1\bin"</span> -Dfile.encoding=UTF-<span class="number">8</span> -classpath <span class="string">"E:\IntelliJ IDEA 2019.1\lib\idea_rt.jar;E:\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;E:\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;E:\jdk1.8\jre\lib\charsets.jar;E:\jdk1.8\jre\lib\deploy.jar;E:\jdk1.8\jre\lib\ext\access-bridge-64.jar;E:\jdk1.8\jre\lib\ext\cldrdata.jar;E:\jdk1.8\jre\lib\ext\dnsns.jar;E:\jdk1.8\jre\lib\ext\jaccess.jar;E:\jdk1.8\jre\lib\ext\jfxrt.jar;E:\jdk1.8\jre\lib\ext\localedata.jar;E:\jdk1.8\jre\lib\ext\nashorn.jar;E:\jdk1.8\jre\lib\ext\sunec.jar;E:\jdk1.8\jre\lib\ext\sunjce_provider.jar;E:\jdk1.8\jre\lib\ext\sunmscapi.jar;E:\jdk1.8\jre\lib\ext\sunpkcs11.jar;E:\jdk1.8\jre\lib\ext\zipfs.jar;E:\jdk1.8\jre\lib\javaws.jar;E:\jdk1.8\jre\lib\jce.jar;E:\jdk1.8\jre\lib\jfr.jar;E:\jdk1.8\jre\lib\jfxswt.jar;E:\jdk1.8\jre\lib\jsse.jar;E:\jdk1.8\jre\lib\management-agent.jar;E:\jdk1.8\jre\lib\plugin.jar;E:\jdk1.8\jre\lib\resources.jar;E:\jdk1.8\jre\lib\rt.jar;E:\MyBatis-study\MyBatis-04\target\test-classes;E:\MyBatis-study\MyBatis-04\target\classes;E:\maven_local_repo\mysql\mysql-connector-java\5.1.46\mysql-connector-java-5.1.46.jar;E:\maven_local_repo\org\mybatis\mybatis\3.5.2\mybatis-3.5.2.jar;E:\maven_local_repo\junit\junit\4.13\junit-4.13.jar;E:\maven_local_repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar"</span> com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 daoTest,getUserByID</span><br><span class="line">Logging initialized using <span class="string">'class org.apache.ibatis.logging.stdout.StdOutImpl'</span> adapter.</span><br><span class="line">PooledDataSource forcefully closed/removed all connections.</span><br><span class="line">PooledDataSource forcefully closed/removed all connections.</span><br><span class="line">PooledDataSource forcefully closed/removed all connections.</span><br><span class="line">PooledDataSource forcefully closed/removed all connections.</span><br><span class="line">Opening JDBC Connection</span><br><span class="line">Created connection <span class="number">1375995437</span>.</span><br><span class="line">Setting autocommit to <span class="keyword">false</span> on JDBC Connection [com.mysql.jdbc.JDBC4Connection@<span class="number">5204062</span>d]</span><br><span class="line">==&gt;  Preparing: select * from mybatis.user where id = ? </span><br><span class="line">==&gt; Parameters: <span class="number">1</span>(Integer)</span><br><span class="line">&lt;==    Columns: id, name, pwd</span><br><span class="line">&lt;==        Row: <span class="number">1</span>, zhuuu, <span class="number">123456</span></span><br><span class="line">&lt;==      Total: <span class="number">1</span></span><br><span class="line">User&#123;id=<span class="number">1</span>, name=<span class="string">'zhuuu'</span>, password=<span class="string">'null'</span>&#125;</span><br><span class="line">Resetting autocommit to <span class="keyword">true</span> on JDBC Connection [com.mysql.jdbc.JDBC4Connection@<span class="number">5204062</span>d]</span><br><span class="line">Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@<span class="number">5204062</span>d]</span><br><span class="line">Returned connection <span class="number">1375995437</span> to pool.</span><br><span class="line"></span><br><span class="line">Process finished with exit code <span class="number">0</span></span><br></pre></td></tr></table></figure>



<h3 id="Log4j的实现"><a href="#Log4j的实现" class="headerlink" title="Log4j的实现"></a>Log4j的实现</h3><p><strong>简介：</strong></p>
<ul>
<li><p>Log4j是Apache的一个开源项目</p>
</li>
<li><p>通过使用Log4j，我们可以控制日志信息输送的目的地：控制台，文本，GUI组件….</p>
</li>
<li><p>我们也可以控制每一条日志的输出格式；</p>
</li>
<li><p>这些可以通过一个配置文件来灵活地进行配置，而不需要修改应用的代码。</p>
</li>
</ul>
<p><strong>使用步骤</strong></p>
<ol>
<li>导入log4j的包(pom.xml中)</li>
</ol>
<figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">dependency</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">groupId</span>&gt;</span>log4j<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>log4j<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">version</span>&gt;</span>1.2.17<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">dependency</span>&gt;</span></span><br></pre></td></tr></table></figure>

<ol start="2">
<li>编写配置文件（在resource文件夹下新建log4j.properties）</li>
</ol>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">#将等级为DEBUG的日志信息输出到console和file这两个目的地，console和file的定义在下面的代码</span></span><br><span class="line">log4j.rootLogger=DEBUG,console,file</span><br><span class="line"></span><br><span class="line"><span class="comment">#控制台输出的相关设置</span></span><br><span class="line">log4j.appender.console = org.apache.log4j.ConsoleAppender</span><br><span class="line">log4j.appender.console.Target = System.out</span><br><span class="line">log4j.appender.console.Threshold=DEBUG</span><br><span class="line">log4j.appender.console.layout = org.apache.log4j.PatternLayout</span><br><span class="line">log4j.appender.console.layout.ConversionPattern=[%c]-%m%n</span><br><span class="line"></span><br><span class="line"><span class="comment">#文件输出的相关设置</span></span><br><span class="line">log4j.appender.file = org.apache.log4j.RollingFileAppender</span><br><span class="line">log4j.appender.file.File=./log/zhuuu.log</span><br><span class="line">log4j.appender.file.MaxFileSize=<span class="number">10</span>mb</span><br><span class="line">log4j.appender.file.Threshold=DEBUG</span><br><span class="line">log4j.appender.file.layout=org.apache.log4j.PatternLayout</span><br><span class="line">log4j.appender.file.layout.ConversionPattern=[%p][%d&#123;yy-MM-dd&#125;][%c]%m%n</span><br><span class="line"></span><br><span class="line"><span class="comment">#日志输出级别</span></span><br><span class="line">log4j.logger.org.mybatis=DEBUG</span><br><span class="line">log4j.logger.java.sql=DEBUG</span><br><span class="line">log4j.logger.java.sql.Statement=DEBUG</span><br><span class="line">log4j.logger.java.sql.ResultSet=DEBUG</span><br><span class="line">log4j.logger.java.sql.PreparedStatement=DEBUG</span><br></pre></td></tr></table></figure>

<ol start="3">
<li>Setting设置日志实现</li>
</ol>
<figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">settings</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">setting</span> <span class="attr">name</span>=<span class="string">"logImpl"</span> <span class="attr">value</span>=<span class="string">"LOG4J"</span>/&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">settings</span>&gt;</span></span><br></pre></td></tr></table></figure>

<ol start="4">
<li>在程序中实现Log4j进行输出</li>
</ol>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//注意导包：org.apache.log4j.Logger</span></span><br><span class="line"><span class="keyword">static</span> Logger logger = Logger.getLogger(MyTest<span class="class">.<span class="keyword">class</span>)</span>;</span><br><span class="line"></span><br><span class="line"><span class="meta">@Test</span></span><br><span class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">selectUser</span><span class="params">()</span> </span>&#123;</span><br><span class="line">    logger.info(<span class="string">"info：进入selectUser方法"</span>);</span><br><span class="line">    logger.debug(<span class="string">"debug：进入selectUser方法"</span>);</span><br><span class="line">    logger.error(<span class="string">"error: 进入selectUser方法"</span>);</span><br><span class="line">    SqlSession session = MybatisUtils.getSession();</span><br><span class="line">    UserMapper mapper = session.getMapper(UserMapper<span class="class">.<span class="keyword">class</span>)</span>;</span><br><span class="line">    List&lt;User&gt; users = mapper.selectUser();</span><br><span class="line">    <span class="keyword">for</span> (User user: users)&#123;</span><br><span class="line">        System.out.println(user);</span><br><span class="line">    &#125;</span><br><span class="line">    session.close();</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<p>输出结果如下：</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br></pre></td><td class="code"><pre><span class="line">E:\jdk1<span class="number">.8</span>\bin\java.exe -ea -Didea.test.cyclic.buffer.size=<span class="number">1048576</span> <span class="string">"-javaagent:E:\IntelliJ IDEA 2019.1\lib\idea_rt.jar=55311:E:\IntelliJ IDEA 2019.1\bin"</span> -Dfile.encoding=UTF-<span class="number">8</span> -classpath <span class="string">"E:\IntelliJ IDEA 2019.1\lib\idea_rt.jar;E:\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;E:\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;E:\jdk1.8\jre\lib\charsets.jar;E:\jdk1.8\jre\lib\deploy.jar;E:\jdk1.8\jre\lib\ext\access-bridge-64.jar;E:\jdk1.8\jre\lib\ext\cldrdata.jar;E:\jdk1.8\jre\lib\ext\dnsns.jar;E:\jdk1.8\jre\lib\ext\jaccess.jar;E:\jdk1.8\jre\lib\ext\jfxrt.jar;E:\jdk1.8\jre\lib\ext\localedata.jar;E:\jdk1.8\jre\lib\ext\nashorn.jar;E:\jdk1.8\jre\lib\ext\sunec.jar;E:\jdk1.8\jre\lib\ext\sunjce_provider.jar;E:\jdk1.8\jre\lib\ext\sunmscapi.jar;E:\jdk1.8\jre\lib\ext\sunpkcs11.jar;E:\jdk1.8\jre\lib\ext\zipfs.jar;E:\jdk1.8\jre\lib\javaws.jar;E:\jdk1.8\jre\lib\jce.jar;E:\jdk1.8\jre\lib\jfr.jar;E:\jdk1.8\jre\lib\jfxswt.jar;E:\jdk1.8\jre\lib\jsse.jar;E:\jdk1.8\jre\lib\management-agent.jar;E:\jdk1.8\jre\lib\plugin.jar;E:\jdk1.8\jre\lib\resources.jar;E:\jdk1.8\jre\lib\rt.jar;E:\MyBatis-study\MyBatis-04\target\test-classes;E:\MyBatis-study\MyBatis-04\target\classes;E:\maven_local_repo\log4j\log4j\1.2.17\log4j-1.2.17.jar;E:\maven_local_repo\mysql\mysql-connector-java\5.1.46\mysql-connector-java-5.1.46.jar;E:\maven_local_repo\org\mybatis\mybatis\3.5.2\mybatis-3.5.2.jar;E:\maven_local_repo\junit\junit\4.13\junit-4.13.jar;E:\maven_local_repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar"</span> com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 daoTest,getUserByID</span><br><span class="line">[daoTest]-info:进入了selectUser方法</span><br><span class="line">[daoTest]-debug:进入了selectUser方法</span><br><span class="line">[daoTest]-error:进入了selectUser方法</span><br><span class="line">[org.apache.ibatis.logging.LogFactory]-Logging initialized using <span class="string">'class org.apache.ibatis.logging.log4j.Log4jImpl'</span> adapter.</span><br><span class="line">[org.apache.ibatis.logging.LogFactory]-Logging initialized using <span class="string">'class org.apache.ibatis.logging.log4j.Log4jImpl'</span> adapter.</span><br><span class="line">[org.apache.ibatis.datasource.pooled.PooledDataSource]-PooledDataSource forcefully closed/removed all connections.</span><br><span class="line">[org.apache.ibatis.datasource.pooled.PooledDataSource]-PooledDataSource forcefully closed/removed all connections.</span><br><span class="line">[org.apache.ibatis.datasource.pooled.PooledDataSource]-PooledDataSource forcefully closed/removed all connections.</span><br><span class="line">[org.apache.ibatis.datasource.pooled.PooledDataSource]-PooledDataSource forcefully closed/removed all connections.</span><br><span class="line">[org.apache.ibatis.transaction.jdbc.JdbcTransaction]-Opening JDBC Connection</span><br><span class="line">[org.apache.ibatis.datasource.pooled.PooledDataSource]-Created connection <span class="number">673186785</span>.</span><br><span class="line">[org.apache.ibatis.transaction.jdbc.JdbcTransaction]-Setting autocommit to <span class="keyword">false</span> on JDBC Connection [com.mysql.jdbc.JDBC4Connection@<span class="number">282003e1</span>]</span><br><span class="line">[com.zhuuu.dao.Mapper.getUserbyID]-==&gt;  Preparing: select * from mybatis.user where id = ? </span><br><span class="line">[com.zhuuu.dao.Mapper.getUserbyID]-==&gt; Parameters: <span class="number">1</span>(Integer)</span><br><span class="line">[com.zhuuu.dao.Mapper.getUserbyID]-&lt;==      Total: <span class="number">1</span></span><br><span class="line">User&#123;id=<span class="number">1</span>, name=<span class="string">'zhuuu'</span>, password=<span class="string">'null'</span>&#125;</span><br><span class="line">[org.apache.ibatis.transaction.jdbc.JdbcTransaction]-Resetting autocommit to <span class="keyword">true</span> on JDBC Connection [com.mysql.jdbc.JDBC4Connection@<span class="number">282003e1</span>]</span><br><span class="line">[org.apache.ibatis.transaction.jdbc.JdbcTransaction]-Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@<span class="number">282003e1</span>]</span><br><span class="line">[org.apache.ibatis.datasource.pooled.PooledDataSource]-Returned connection <span class="number">673186785</span> to pool.</span><br><span class="line"></span><br><span class="line">Process finished with exit code <span class="number">0</span></span><br></pre></td></tr></table></figure>



<h2 id="分页的实现"><a href="#分页的实现" class="headerlink" title="分页的实现"></a>分页的实现</h2><h3 id="为什么需要分页？"><a href="#为什么需要分页？" class="headerlink" title="为什么需要分页？"></a>为什么需要分页？</h3><ul>
<li>在学习mybatis等持久层框架的时候，会经常对数据进行增删改查操作，使用最多的是对数据库进行查询操作</li>
<li>如果查询大量数据的时候，我们往往使用分页进行查询，也就是每次处理小部分数据，这样对数据库压力就在可控范围内。</li>
</ul>
<h3 id="limit实现分页"><a href="#limit实现分页" class="headerlink" title="limit实现分页"></a>limit实现分页</h3><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line">#语法</span><br><span class="line">select * from table Limit startIndex,pageSize</span><br><span class="line"></span><br><span class="line">#如:</span><br><span class="line">SELECT * FROM table LIMIT 5,10; &#x2F;&#x2F; 检索记录行 6-15 </span><br><span class="line"></span><br><span class="line">#如果只给定一个参数，它表示返回最大的记录行数目：    </span><br><span class="line">SELECT * FROM table LIMIT 5; &#x2F;&#x2F;检索前 5 个记录行 </span><br><span class="line"></span><br><span class="line">#换句话说，LIMIT n 等价于 LIMIT 0,n。</span><br></pre></td></tr></table></figure>



<p>使用步骤：</p>
<ol>
<li>修改Mapper文件</li>
</ol>
<figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">select</span> <span class="attr">id</span>=<span class="string">"selectUser"</span> <span class="attr">parameterType</span>=<span class="string">"map"</span> <span class="attr">resultType</span>=<span class="string">"user"</span>&gt;</span></span><br><span class="line">    select * from user limit #&#123;startIndex&#125;,#&#123;pageSize&#125;</span><br><span class="line"><span class="tag">&lt;/<span class="name">select</span>&gt;</span></span><br></pre></td></tr></table></figure>

<ol start="2">
<li>Mapper接口修改入参为map</li>
</ol>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//选择全部用户实现分页</span></span><br><span class="line"><span class="function">List&lt;User&gt; <span class="title">selectUser</span><span class="params">(Map&lt;String,Integer&gt; map)</span></span>;</span><br></pre></td></tr></table></figure>

<ol start="3">
<li>在测试类中传入参数</li>
</ol>
<ul>
<li>推断：起始位置 = （当前页面 - 1 ） * 页面大小</li>
</ul>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">import</span> com.zhuuu.dao.Mapper;</span><br><span class="line"><span class="keyword">import</span> com.zhuuu.pojo.User;</span><br><span class="line"><span class="keyword">import</span> com.zhuuu.utils.MybatisUtils;</span><br><span class="line"><span class="keyword">import</span> org.apache.ibatis.session.SqlSession;</span><br><span class="line"><span class="keyword">import</span> org.junit.Test;</span><br><span class="line"></span><br><span class="line"><span class="keyword">import</span> java.util.HashMap;</span><br><span class="line"><span class="keyword">import</span> java.util.List;</span><br><span class="line"></span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">daoTest</span> </span>&#123;</span><br><span class="line">    <span class="meta">@Test</span></span><br><span class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">test</span><span class="params">()</span></span>&#123;</span><br><span class="line">        SqlSession session = MybatisUtils.getSession();</span><br><span class="line">        Mapper mapper = session.getMapper(Mapper<span class="class">.<span class="keyword">class</span>)</span>;</span><br><span class="line"></span><br><span class="line">        <span class="keyword">int</span> curentPage = <span class="number">1</span>;<span class="comment">//第几页</span></span><br><span class="line">        <span class="keyword">int</span> pageSize = <span class="number">2</span>;<span class="comment">//每页显示几个</span></span><br><span class="line"></span><br><span class="line">        HashMap&lt;String, Integer&gt; map = <span class="keyword">new</span> HashMap&lt;String, Integer&gt;();</span><br><span class="line">        map.put(<span class="string">"startIndex"</span>,(curentPage-<span class="number">1</span>)*pageSize);</span><br><span class="line">        map.put(<span class="string">"pageSize"</span>,pageSize);</span><br><span class="line"></span><br><span class="line">        List&lt;User&gt; userList = mapper.getUserList(map);</span><br><span class="line">        <span class="keyword">for</span> (User user : userList) &#123;</span><br><span class="line">            System.out.println(user);</span><br><span class="line">        &#125;</span><br><span class="line">        session.close();</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="RowBounds分页"><a href="#RowBounds分页" class="headerlink" title="RowBounds分页"></a>RowBounds分页</h3><ul>
<li>除了使用Limit在SQL层面实现分页，也可以使用RowBounds在Java代码层面实现分页，</li>
<li>当然此种方式作为了解即可。我们来看下如何实现的！</li>
</ul>
<p><strong>步骤：</strong></p>
<ol>
<li>mapper接口</li>
</ol>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//选择全部用户RowBounds实现分页</span></span><br><span class="line"><span class="function">List&lt;User&gt; <span class="title">getUserByRowBounds</span><span class="params">()</span></span>;</span><br></pre></td></tr></table></figure>

<ol start="2">
<li>mapper.xml文件</li>
</ol>
<figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">select</span> <span class="attr">id</span>=<span class="string">"getUserByRowBounds"</span> <span class="attr">resultType</span>=<span class="string">"user"</span>&gt;</span></span><br><span class="line">  select * from user</span><br><span class="line"><span class="tag">&lt;/<span class="name">select</span>&gt;</span></span><br></pre></td></tr></table></figure>

<ol start="3">
<li><p>测试类    </p>
<p>在这里使用RowBounds类</p>
</li>
</ol>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">@Test</span></span><br><span class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">testUserByRowBounds</span><span class="params">()</span> </span>&#123;</span><br><span class="line">    SqlSession session = MybatisUtils.getSession();</span><br><span class="line"></span><br><span class="line">    <span class="keyword">int</span> currentPage = <span class="number">2</span>;  <span class="comment">//第几页</span></span><br><span class="line">    <span class="keyword">int</span> pageSize = <span class="number">2</span>;  <span class="comment">//每页显示几个</span></span><br><span class="line">    RowBounds rowBounds = <span class="keyword">new</span> RowBounds((currentPage-<span class="number">1</span>)*pageSize,pageSize);</span><br><span class="line"></span><br><span class="line">    <span class="comment">//通过session.**方法进行传递rowBounds，[此种方式现在已经不推荐使用了]</span></span><br><span class="line">    List&lt;User&gt; users = session.selectList(<span class="string">"com.zhuuu.mapper.UserMapper.getUserByRowBounds"</span>, <span class="keyword">null</span>, rowBounds);</span><br><span class="line"></span><br><span class="line">    <span class="keyword">for</span> (User user: users)&#123;</span><br><span class="line">        System.out.println(user);</span><br><span class="line">    &#125;</span><br><span class="line">    session.close();</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>



<h2 id="分页插件："><a href="#分页插件：" class="headerlink" title="分页插件："></a>分页插件：</h2><p>官方文档：<a href="https://pagehelper.github.io/" target="_blank" rel="noopener">https://pagehelper.github.io/</a></p>
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